XRT72L50 Datasheet, PDF (81/471 Pages) Exar Corporation – SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER
REV. 1.2.1
2.3.3.7 Receive E3 LAPD Control Register (E3, ITU-T G.832)
RxE3 LAPD Control Register (Address = 0x18)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Not Used
DL from NR
RxLAPD
Enable
RxLAPD
Interrupt
Enable
RxLAPD
Interrupt
Status
RO
RO
RO
RO
R/W
R/W
R/W
RUR
0
0
0
0
0
0
0
0
Bit 3 - DL from NR
This Read/Write bit-field allows the user to specify whether the LAPD Receiver should retrieve the bytes,
comprising the incoming LAPD Message frame, from the NR byte-field, or from the GC byte-field, within each
incoming E3 frame.
Writing a "1" configures the LAPD Receiver to retrieve the incoming LAPD Message frame octets from the NR
byte-field, within each incoming E3 frame. Writing a "0" configures the LAPD Receiver to retrieve the incoming
LAPD Message frame octets from the GC byte.
Bit 2 - RxLAPD Enable
This Read/Write bit-field allows the user to enable or disable the LAPD Receiver, for reception of incoming
LAPD Message frames from the Remote LAPD Transmitter.
Writing a "1" to this bit-field enables the LAPD Receiver. Writing a "0" to this bit-field disables the LAPD
Receiver.
Bit 1 - RxLAPD (Received LAPD Message) Interrupt Enable
This Read/Write bit-field allows the user to enable or disable the Received LAPD Message frame interrupt.
Setting this bit-field to "1" enables this interrupt. Setting this bit-field to "0" disables this interrupt.
NOTE: For more information on this interrupt, refer to Section 6.3.3.
Bit 0 - RxLAPD (Received LAPD Message) Interrupt Status
This Reset-upon-Read bit-field will be set to "1" if the Receipt of New LAPD Message frame interrupt has
occurred since the last read of this register.
The Receive DS3/E3 Framer block will generate this Receipt of New LAPD Message frame interrupt when the
LAPD Receiver has received a complete LAPD Message frame from the Remote LAPD Transmitter.
NOTE: Please see Section 6.3.6.2.12 for a more detailed discussion of this interrupt.
2.3.3.8 Receive E3 LAPD Status Register (E3, ITU-T G.832
RxE3 LAPD Status Register (Address = 0x19)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Not Used Rx ABORT
RxLAPDType[1:0]
RxCR
Type
RxFCS
Error
End of
Message
Flag
Present
RO
RO
RO
RO
RO
RO
RO
RO
0
0
0
0
0
0
0
0
Bit 6 - RxAbort (Receive Abort Sequence)
This Read-Only bit-field indicates whether or not the LAPD Receiver has detected the occurrence of an Abort
Sequence (e.g., a string of seven or more consecutive "1’s") from the remote LAPD Transmitter. A "0" in this
bit-field indicates that no Abort-Sequence has been detected. A "1" in this bit-field indicates that the Abort-
Sequence has been detected.
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